The subject matter disclosed herein relates to propeller systems. More specifically, the subject disclosure relates propeller blade pitch lock systems. Propeller-driven craft, for example, airplanes, helicopters or hovercraft, often include pitch change mechanisms that allow for the pitch of the propeller blades to be changed depending on, for example, operating conditions, to increase performance of the propeller. Such systems are typically hydraulically-actuated and have a fail-fixed (or pitch-lock) feature in which the pitch of the propeller blades is locked in position in the event of a hydraulic failure.
In some instances, it is desirable to provide a device to adjust the pitch of the propeller blades of such a hydraulic system even after a hydraulic failure occurs engaging the pitch-lock feature.